1. Field of the Invention
The present invention relates to a method and an apparatus for correcting curling of a film and a method of manufacturing a laminated film.
2. Description of the Related Art
Among polymer films, cellulose acylate films and the like have features of excellent transparency, flexibility, and so on. There are a variety of uses for polymer films, such as a window film for being adhered to window glass, a touch panel film, an ITO base film, a membrane switch film, a 3-dimensional decoration film, an optically functional film for flat panel displays, and the like.
The above uses may include cases in which the hand, a towel, a touch pen, or the like comes into contact with or brushes the surface of the polymer film. In such cases, in order to prevent the surface of the polymer film from being damaged, a hard coating layer that is harder than the polymer film is provided on the surface of the polymer film.
An example of the method of manufacturing a polymer film having a hard coating layer on the surface will be described. Firstly, a membrane having a solvent and an ultraviolet-curing agent (hereinafter referred to as an ultraviolet-curable membrane) is formed on the surface of the polymer film (hereinafter referred to as a membrane-forming process). Next, the solvent is evaporated from the ultraviolet-curable membrane. Thirdly, the ultraviolet-curing agent included in the ultraviolet-curable membrane is polymerized by irradiation of ultraviolet rays (referred to as a polymerization process). This polymerization process enables the obtainment of a membrane including the polymer of the ultraviolet-curing agent (hereinafter referred to as a polymer membrane) from the ultraviolet-curable membrane. In this manner, a laminated film having a base layer composed of the polymer film and a hard coating layer composed of the polymer membrane can be manufactured.
However, the polymerization reaction of the ultraviolet-curing agent makes the laminated film curled so that the hard coating layer faces inward. Therefore, the curling of the laminated film was corrected by a process in which water vapor was sprayed onto the laminated film that had undergone the polymerization process (hereinafter referred to as the water vapor-contacting process) (for example, JP2003-195051A) In addition, even in a single-layer film, which is not a laminated film, there are cases in which the winding tendency, uneven distribution of the humidity and the like, and the single-layer film makes the inside and outside states of the film different, and curling occurs.